The Long-Term 2 Enhanced Surface Water Treatment Rule also calls for continuous monitoring at the entry point to the distribution system with a minimum of ______ of chlorine residual.

The Long-Term 2 Enhanced Surface Water Treatment Rule also calls for continuous monitoring at the entry point to the distribution system with a minimum of ______ of chlorine residual.

• A. a trace
• B. 0.2 mg/L
• C. 0.5 mg/L
• D. 1.0 mg/L

Answer: (B)

The rule requires continuous monitoring of disinfectant residual at the entry point to the distribution system, with a minimum free chlorine residual of 0.2 mg/L. This ensures that after treatment there’s enough disinfectant entering the network to prevent microbial growth as water ages and travels through pipes. The other options don’t fit because a trace isn’t a defined concentration, and 0.5 mg/L or 1.0 mg/L are higher than the required minimum. Keeping at least 0.2 mg/L helps maintain protection throughout the distribution system.

The rule requires continuous monitoring of disinfectant residual at the entry point to the distribution system, with a minimum free chlorine residual of 0.2 mg/L. This ensures that after treatment there’s enough disinfectant entering the network to prevent microbial growth as water ages and travels through pipes. The other options don’t fit because a trace isn’t a defined concentration, and 0.5 mg/L or 1.0 mg/L are higher than the required minimum. Keeping at least 0.2 mg/L helps maintain protection throughout the distribution system.